Development of exposure chamber for investigation of inhaled chronic health effect of airbone particles

由于工作和大气环境中粉尘控制的改善，对吸入粉尘的慢性健康影响的调查比急性健康影响的调查更为重要。因此，在动物实验中，暴露室内的粉尘浓度和粒径分布必须长时间保持恒定。此外，希望所述颗粒不结块并均匀分散。本文研制了一种新型连续螺旋给料和溢流管的流化床粉尘发生器，用于长期慢性吸入毒性研究。该发电机具有以下优点：可以长时间操作。粉尘浓度可任意改变。可以产生多种气溶胶颗粒。维护和操作方便。以Wister雄性大鼠为实验对象，研究了其吸入系统（含粉尘发生器、暴露室和气液固分离器）的性能。观察到以下结果：暴露室内一年的日平均浓度为38.5 <+！-> 11.1 mg/ <m^3>（高暴露组）和5.0 <+！-> 2.1 mg/ <m^3>（低暴露组）暴露过程中，煤粉煤灰气溶胶在暴露室内的质量中值气动直径为2.7 <微> m。暴露大鼠肺中观察到大量粉煤灰颗粒。通过对粉煤灰中含铝量的分析，定量测定了粉煤灰的体负荷。暴露大鼠肺中煤飞灰沉积量显著增加。我相信本研究开发的吸入系统对于研究吸入粉尘的慢性健康影响是非常有用的。

As a result of improved dust control in work and atmospheric environments, investigations of the chronic health effects of inhaled dust have become much more important than the acute ones. In animal experiments, therefore, the dust concentration and size distribution in the exposure chamber must be kept constant over a long period. Also, it is desirable that the particles be unagglomerated and evenly dispersed. In this study a new fluidized bed dust generator with continuous screw feeder and overflow pipe was developed for long-term chronic inhalation toxicity studies. This generator has the following advantages:1. It is possible to operate for a long time.2. The dust concentration can be changed arbitrarily.3. Many kinds of aerosol particles can be generated.4. Maintenance and operation are easy.The performance of inhalation system, consisted of dust generator, exposure chambers and gas-liquid-solid separator, were investigated by Wister male rats exposed to coal fly ash aerosol for one-year.The following results were observed.1. The daily average concentrations in the exposure chamber for one-year were 38.5 <+!-> 11.1 mg/ <m^3> (high exposure group) and 5.0 <+!-> 2.1 mg/ <m^3> (low exposure group).2. The mass median aerodynamic diameter of coal fly ash aerosol in the exposure chamber was 2.7 <micro> m during the exposure.3. Many coal fly ash particles were observed in exposed rat lung.4. The body burdens of coal fly ash were measured quantitatively by an analysis of aluminium contained in coal fly ash.5. The deposed coal fly ash in exposed rat lung was significantly incresed.I believe that the inhalation system developed in this study is extremely useful for investigating chronic health effects of inhaled dusts.